Etch Effects on Surface loss in High Quality Aluminum on Silicon Superconducting Coplanar Resonators*

Superconducting coplanar resonators are a powerful tool for studying capacitive loss from two level states (TLS's) in superconducting qubits. We have found evidence that standard processing of aluminum on sapphire superconducting devices leaves behind $\approx$2 nm organic residues which can contribute to loss at the Q$> 10^{6}$ level that we are presently working with. Removing these residues is possible on a silicon substrate as it allows various sidewall etchings and profilings via chemical and physical etches. I will present recent Q factor measurements of aluminum on silicon resonators that were defined through a variety of etching conditions.